热排水固结法作用机理及模型试验研究

Thermal drainage consolidation method is a new and very promising technology in soft foundation treatment. Under such complex loading conditions as temperature, stress and seepage flow, mechanism of the thermal drainage consolidation, evaluation of reinforcement effect and optimization of design parameters are key scientific problems required to be solved. A method of combining laboratory test, model test, theoretical modeling with numerical analysis is used in this subject. .Firstly, heat penetration, hot deformation and hot stress path test are carried out by sampling from the smearing area and undisturbed area of shaft foundation, and such temperature effect as heat penetration, thermal hardening, thermal softening and its evolutionthe are obtained quantitatively, then the mechanism of thermal drainage consolidation method are revealed. .Secondly, comparison model test of thermal drainage consolidation method with drainage consolidation method are developed on basis of the laboratory test, validity and reinforcement effect of thermal drainage consolidation method is evaluated. .Finally, a thermo-elastic-plastic constitutive equation for the soft clay in which stress path can be considered and numerical calculation model for thermal drainage consolidation method are presented. Then mutual verification are executed on numerical calculation results and experimental results, furthermore the optimized design parameters and treatment measures of the thermal drainage consolidation method in soft foundation is presented. The results of this subject, on the one hand, can reveal the mechanical properties of soft soil under complex environmental conditions, develop multi-physical field soil mechanics and promote inter- disciplinary, on the other hand can provide an important scientific and technical support for the design and application of thermal drainage consolidation method.

热排水固结法是一项新型的、非常有潜力的软基处理技术，在温度、应力和渗流复杂加载条件下，热排水固结作用机理、加固效果评价和设计参数优化等是亟待解决的关键科学问题。为此，本项目采用室内试验、模型试验、理论建模和数值模拟相结合的方法，对竖井涂抹区和未扰动区土体开展热渗透、热变形和热应力路径试验，定量地分析热渗透、热硬化、热软化等温度效应及其演化规律，揭示热排水固结法作用机理。其次，开展热排水固结与排水固结模型试验，评价热排水固结法的有效性及其加固效果。在此基础上，建立黏性土应力路径热弹塑性本构方程和数值计算模型，对热排水固结试验模型进行数值模拟，并与模型试验结果相互验证，进而优化热排水固结法设计参数，提出相应的技术措施。研究成果一方面可揭示复杂环境条件下软土的力学特性，发展多物理场土力学，促进学科交叉，另一方面为我国软土地区热排水固结法的设计和应用提供重要的科学和技术支撑。

本项目围绕热排水固结法的作用机理及加固效果开展试验、理论和数值研究，首先从温度对土的粘滞性、渗透性影响出发，阐明了热排水固结法的可行性；对不同温度作用下土(正常固结和超固结土OCR，不同加载条件和应力路径)的变形、强度开展了系统的研究，获得了温度对土体变形和强度有较大改善的结果；进而开展了多组模型试验，包括单井、群井条件，不同温度作用，并与常温条件下的工况进行了对比，揭示了温度对软基处理具有明显的作用效果，可以加速水的排除，缩短软基处理时间，提高土的强度，减小工后沉降；最后，通过建立考虑温度影响的非线弹性本构、考虑先期固结压和应力路径影响的热弹塑性本构模型，并以三轴试样、模型试验为原型开展数值计算，获得不同温度、耦合与不耦合模型对热排水固结软基处理结果的影响。结合研究计划执行情况，本项目基本完成了各项研究目标，从理论、试验和机理上较好地阐明了热排水结法机理，为热排水结法的实际应用提供了理论依据。